Alexios Mosele () or Musele/Mousele (Μουσελέ) was a Byzantine aristocrat and general, chosen by Emperor Theophilos (r. 829–842) for a time as his heir, betrothed to his daughter Maria and raised to the supreme dignity of Caesar. He campaigned in the Balkans, recovering territory from the Slavs, and fought with some success in Sicily against the Arabs. Recalled to Constantinople on suspicion of plotting to usurp the throne, he was imprisoned but later pardoned and allowed to retire to a monastery, where he spent the remainder of his days. Biography Alexios was possibly the son or the grandson of the general Alexios Mosele, who had been active under Constantine VI (r. 780–797), although Byzantine chroniclers record that he was descended from the Krenites family. A brother named Theodosios, who held the high court title of patrikios, is also recorded. Sometime between 836 and 839, Alexios was engaged to the princess Maria, Emperor Theophilos's youngest and favourite daughter, despite the fact that she was an infant. Theophilos had no male heir at the time, and this move was evidently intended as marking out Alexios as his heir apparent. He was progressively promoted to patrikios and anthypatos, then to magistros and eventually to Caesar. He was the only person known to have been promoted to the rank during Theophilos's reign, and may indeed have been raised to it as early as 831, when the presence of an unnamed Caesar is attested at an imperial triumph. Alternatively, it may be a reference to another, otherwise unknown, holder of the title, who probably died shortly after. In summer 836, Mosele, recently promoted to Caesar, was dispatched with an army against the Bulgars in Thrace. Instead of confronting them, however, he focused on recovering for the Byzantine Empire the coastal strip between the rivers Nestos and Strymon, which had been abandoned to the local Slavs by the Byzantine-Bulgarian Treaty of 816. In this way, he restored the direct land connection between Thrace and Thessalonica, the Empire's major Balkan city. After founding a new city, named Caesaropolis after himself, he returned to Constantinople. Alexios may have participated in Theophilos's successful campaign against Melitene in 837, as he is recorded to have participated in the triumph that followed the emperor's return. This, however, is disputed by some scholars. In 838, Mosele was sent on an expedition against the Arabs in Sicily. There, he achieved a number of